Products from refinery such as gasoline, diesel and the like are produced by blending various component streams in order to meet product specifications. For example, gasoline blend is produced in a refinery by blending streams such as reformate, alkylate, FCC naphtha, straight run naphtha, ethanol, TAME and the like. Gasoline production is constrained by property specifications such as RON, MON, RVP, density, distillation, sulfur, aromatics, olefins, benzene and the like. Each of these component streams have different properties and are blended in various proportions to meet gasoline specifications.
These component streams have minor to large property fluctuations on a day to day basis. Based on the component stream property values, the blend proportions are altered to meet the specifications. Experimental techniques and tests for analysis of gasoline include RON/MON by CFR engine test (ASTM D2700, EN 25163, IP 236, ASTM D2699, EN 25164, IP 237), distillation by ASTM D86, RVP by ASTM D323, API/density by ASTM D-287, D-1298, sulfur content by X-Ray ASTM D-4294/D-2622, benzene and total aromatics by D3606, D5769, D5580, aromatics/olefins by ASTM D-1319, mercaptan sulfur by D-3227 etc. For diesel, these techniques include cetane number ASTM D-613, IP 41, EN ISO 5165, distillation by ASTM D86, cetane index by ASTM D-4737, IP 380, EN 4264, ASTM D-976, API/density by ASTM D-287, D-1298, flash point measurements, cloud point/cold filter plugging point measurements, sulfur by ASTM D2784, D3246, D3961, D4468, D6212, D6667, D5453, D7039, (EDXRF) ASTM D4294 etc.
However, these approaches for analysis of the component streams suffer from drawbacks. Firstly, the above mentioned techniques for analysis of the component streams are time consuming Depending upon the lab set up the time period required for conducting these analytical tests can be one to two days. This makes it practically impossible to analyze all the component streams on a day to day basis.
In order to meet a specification, schedulers have to rely on their judgment while blending the different component streams. This approach can sometimes results in (a) quality give away (QGA) i.e. products have better properties than what is needed/specified, or (b) product failures i.e. products do not meet specifications.
There is thus felt a need for a system and a method for preparation of hydrocarbon blends with pre-determined specification by blending different component streams that involves frequent regulation of the proportion of each component stream during the blending and wherein the regulation of the proportion of each of the component stream in the blend is carried out on the basis of frequent analysis of the properties or compositions of each of the component streams.